1. Field of the Invention
The invention relates to a method of nanoimprinting a piezoelectric polymeric material using a nanoimprinting template under an imprinting temperature less than the Curie temperature of the piezoelectric polymeric material for forming high aspect ratio nanopillars.
2. Description of the Related Art
Piezoelectric materials can be used for making transducers, and include ceramic type and polymeric type piezoelectric materials. In “Flexible Dome and Bump Shape Piezoelectric Tactile Sensors Using PVDF-TrFE Copolymer,” Journal of Microelectromechanical Systems, 2008, 17, 334-341, Chunyan Li et al. disclose a sensor made from a piezoelectric material having a microstructure that can improve the sensitivity of the sensor. The microstructure is in micro scale and is formed by spin-coating techniques.
In “Large Area High Density Sub-20 nm SiO2 Nanostructures Fabricated by Block Copolymer Template for Nanoimprint Lithography,” 2009 American Chemical Society, Vol. 3, No. 9, 2601-2608, 2009, Park et al. disclose a nanoimprinting method for forming large area high density sub-20 nanometer nanopillars or nanoholes. The conventional method can form sub-20 nanometer nanopillars or nanoholes on materials, such as polymethyl methacrylate (PMMA), poly(dimethylsiloxane) (PDMS), and poly(3-hexylthiophene) (P3HT). However, the conventional method can only produce nanopillars having a low aspect ratio (up to 2.5 only). In the field of material science, an aspect ratio of less than 5 is considered as a low aspect ratio.
In addition, it is commonly known in the art that when it is desired to form pillars on a material, the imprinting template used for imprinting is required to have holes formed therein, and when it is desired to form holes in the material, the imprinting template is required to have pillars formed thereon.